In recent years, a method has been developed to enhance tryptophan “Trp” availability to brain, and so potentially serotonin function, by administering TRP-rich dietary proteins/hydrolysates. These include the whey protein alpha-lactalbumin, and a casein hydrolysate. Since the Trp present in these proteins/hydrolysates competes with Large Neutral Amino Acids (LNAAs which are tyrosine, phenylalanine, leucine, isoleucine and valine) for transport across the blood-brain barrier, a high Trp/LNAA ratio is desired, and this ratio is difficult to achieve with these protein/hydrolysates.
DSM has developed a hen egg white lysozyme hydrolysate formulation that contains fewer competing LNAAs, and is sold under the trademark lumiVida™. LumiVida™ has recently been shown to be more effective in raising plasma Trp/LNAA ratios than either alpha-lactalbumin or L-Trp alone and 4 g lumiVida™ was still able to raise Trp/LNAA ratio when ingested together with milk protein. This hydrolysate has been described in WO 2008/052995, which is hereby incorporated by reference.
Typical dosages which are used in WO 2008/052995 are quite large (10 grams hydrolysate per liter liquid; 14 grams per 300 ml drink) as this appears to be necessary for a significant increase of serum Trp/LNAA ratios, and ultimately increase the Trp availability to the brain. However, the peptides are rather bitter tasting. It would be desirable to have a formulation which was pleasant tasting and also provides enough Trp to the brain as to be effective.